David Blunkett this week trod where no home secretary has trod before. He told a BBC interviewer that a new high security passport card to be introduced in 2005 would become a de facto national identity card.
Blunkett's announcement ends a political taboo going back to 1952 when the wartime national identity card scheme was abolished.
A previous plan to revive identity cards in 1993 ran out of steam because the Conservative government at the time didn't like the idea of the European flag appearing on the card. There was also no proof that the card would perform its stated purpose: fighting crime. Finally, the technical barriers to joining up the necessary back-office IT systems were seen as insuperable.
What has changed in the meantime is the arrival of biometrics: the technology of identifying an individual with a biological characteristic, until now usually a fingerprint. However, Blunkett indicated that a scan which shows the pattern of blood vessels in the holder's iris is now the preferred technology.
Blunkett was speaking after a meeting of interior ministers of G8 countries agreed to work together on the technology to enforce border security.
In fact, the UK's plans are already well advanced. The Passport Agency's latest corporate plan, published last week, reveals that within two years, passport books could contain a chip containing the holder's biometric data. A similar chip would appear on a proposed passport card. "Progress has been made and, subject to an adequate level of demand, we expect to launch a card in 2005," the plan says.
The International Civil Aviation Organisation has already agreed in principle that all passports should include a biometric identifier. It has nominated facial images - digitised versions of passport photographs - as the most promising technology. The US government says that from October next year, it will allow visa-free travellers only from countries that include biometrics in passports.
All this is great news for the electronic security industry. At last week's Infosecurity Exhibition in London, electronics giant NEC demonstrated a facial recognition system that it says is robust enough for everyday security use. The software automatically homes in on the eyes, face and overall head shape from a camera image and matches the patterns with those on the ID chip.
Singapore is already using fingerprint biometrics to carry out checks on residents arriving at Changi Airport or over the causeway from Malaysia. Their card is inserted into a slot and a forefinger into a fingerprint reader. As long as the fingerprint matches the template on the card (and your finger is not too sweaty or shaky), you pass straight through. Each verification "takes less than a sub-second", claims NEC.
Although several European countries, including Belgium and Italy, are already encoding biometrics on identity cards, plans to introduce a passport card in Britain are still technically on hold. Confusing the issue is a proposal to issue an identity card to prove entitlement to social security benefits and NHS treatment.
The entitlement card will have to carry biometrics if it is to be any use against identity fraud: otherwise it would be hard to stop one individual applying for more than one identity document. Late last year, the Home Office said it was considering an iris pattern supported by a facial image.
Blunkett's statement suggests that he is moving towards issuing a dual purpose biometrically encoded passport and entitlement card. This is not as easy as it sounds. First, the two cards would be issued to different populations: the passport database is of citizens (and only 80% of us hold them), while the entitlement card would be available to legal residents of any nationality.
Finally, there are practical difficulties with a single card. People who have booked an expensive holiday won't want to risk losing their passports the week before, so may prefer to carry a less valuable ID in their pocket. To confuse the picture further, many frequent travellers will need a passport book as well as a passport card.
Although Blunkett has taken the political plunge, there will be plenty of devil in the detail.
